E browning



Jan. 31, 1956 w. E. BROWNING 2,732,768

BREECH-BOLT LOCKING MECHANISM FOR AUTOMATIC SHOTGUNS Filed Jan. 21, 1952 2 Sheets-Sheet l 422 26 I6 0 L; 4 33 55 I I I3 3/ 36 $2 350 I5 54 20 23 I2 3/ 28-! 28 I0 I I 56 F IG. 3.

\l/ll/ l l llllllllllllll JQ L-I Bnbentor:

WALTER E. BROWNING,

Gttorneg 5.

Jan. 31', 1956 w. E. BROWNING 2,732,768

BREECH-BOLT LOCKING MECHANISM FOR AUTOMATIC SHOTGUNS Filed Jan. 21, 1952 2 Sheets-Sheet 2 2/\ F/G. l0.

Zhwentor: d/XLTER E. BROWNING, u Wu-05 M11 United States Patent BREECH-BOLT LOCKING MECHANISM FOR AUTOMATIC SHOTGUNS This invention relates to the operating mechanism of small firearms utilizing explosive cartridges. It is concerned principally with so-called automatic shotguns, and has particular reference to mechanism whereby the breech-boltof such guns is automatically locked in position following each recoil, as a safety measure, but is released during the recoil following each firing to permit normal cartridge ejection and reloading.

A principal object of my invention is to make possible-and practical-unlocking of the breech-bolt assembly without movement of the barrel relative to the. receiver, thereby eliminating the customary barrel extension and reducing the usual drop from the top of the receiver to the top of the barrel. In this manner the height of the front sight, as customarily positioned on the front of the barrel, is reduced, and accuracy and easeof aim are increased, while danger of damage to the gunsight is largely eliminated.

A further important object is to achieve an effective and completely positive locking of the firing pin against accidental movement at such times as the breech-bolt assembly is unlocked and free to move relative to the receiver.

A primary structural feature of the invention is the provision of a freely movable inertia block operatively connected with a locking element, so as to be actuated by the force of and during the period of recoil to withdraw the locking elementfrom its normally maintained locking position.

1 The inertia block is arranged to move forwardly relative to the backward movement of the receiver, breechbolt, barrel, and stock of the gun on recoil, and 'therefore this movement may be considered to be longitudinal in character. The locking element is, however, arranged to move transversely. I prefer to utilize a cam groove and pin connection between the inertia block and locking element as motion transmitting and directing means. v

' The locking element is preferably in the form of a deeply slotted block straddling the firing pin and movable upwardly at right angles to the path of action of the inertia block and into a suitably formed and positioned locking notch provided in the receiver. Such locking block and the firing pin are provided with respective, mutually correlated and interacting locking formations.

' The entire mechanism is compact and relatively simple in construction. It is designed to require a minimum modification of the receiver and associated structure conventional for guns of the type concerned, though, also, to make possible the streamlining of such receiver Further objects and features of the invention will become apparent from the following detailed description of the particular preferred embodiment illustrated by way of example in the accompanying drawings.

In the drawings:

Fig. 1 represents a fragmentary top plan view of a shotgun embodying my invention, portions of the barrel, magazine tube, and the gunstock being broken away for convenience of illustration, and portions of the top wall of the receiver being broken out to reveal otherwise hidden mechanism;

Fig. 2, a vertical section taken on the line 2-2 of Fig. 1 as respects the receiver, but the breech-bolt mechanism, trigger mechanism, and firing pin being shown largely in elevation, the various component parts appearing in the firing or locked position;

Fig. 3, a view similar to that of Fig. 2, but showing the unlocked position of the parts resulting from recoil action following the pulling of the trigger and the firing of the gun;

Fig. 4, a view similar to those of Figs. 2 and 3, but

showing the position of the parts resulting from the in, a manner facilitating sighting of the gun during action .tion, trouble free in use, and capable of production at a cost comparableto existing types of breech-bolt mechanism.

action of residual gases upon the unlocked breech-bolt assembly; I

Fig. 5, a fragmentary elevation of the side which, in Fig. l, is uppermost ofthe sheet;

' Fig. 6 a detail view in central vertical section of the breech-bolt mechanism per se, drawn to a considerably enlarged scale, the positions of the several parts corresponding to those of Fig. 2, i. e. the positions assumed in locking the breech-bolt mechanism to the receiver;

Fig. 7, a view corresponding to that of Fig. 6, but the positions of the several parts corresponding to those of either Fig. 3 or Fig. 4, i. e. the positions assumed for unlocking the breech-bolt mechanism;

' Fig. 8, a transverse section taken on the line 8-8 of Fig. 6;

Fig. 9, a similar section taken on the line 99 of Fig. 6, but showing fragmentary portions of contiguous structure; and

Fig. 10, a fragmentary horizontal sectiontaken on the line 10-10 of Fig. 7.

Referring to the drawings:

The breech-bolt assembly is indicated generally by the numeral 10, and is slidably mounted within a receiver 11.

Receiver Except for certain details described hereinafter, the receiver is of essentially conventional formation, being provided with apertures at its forward end for receiving the usual assembly of barrel 12 and magazine tube 13, witha formation at its rearward end adapted to tie in with the usual gunstock 14, and with a bottom'which is open for the reception of a trigger plate and associated mechanism designated generally 15.

The opposite interior side walls of the receiver 11 are grooved to provide guideway channels 16, Figs. 2 and 3, for the breech-bolt assembly in its backward movement, see Fig. 4, as occasioned by the residual gases in the barrel 1'2, acting upon such breech-bolt assembly in its unlocked condition.

One of the opposite side walls is apertured, as at 17, Figs. 4 and 5, as a spent cartridge ejection portand to accommodate the projection, outwardly from the receiver, of a manually actuatable thumb push 18, the latter being integral with a slide 19 designed to permit manual unlocking of the breech-bolt assembly when "desired. A rearward, slideway extension 17a of the aperture 17 permits the thumb push 18 and slide 19 to travel through a full operating stroke.

The interior face of the top wall of the receiver 11 is recessed... at 20.. Figs. 2. and 4.. for snu ly receiving.

Breech-bolt assembly in general The breech-bol assembly .10; see F gs- 6 thr ugh 0,

c mpr esa e h= dlt hous n 2.1. wh serves s a arria e for the other p r of the assem y- Such housing 21 is provided; with outwardly projecting feet 22 at th bo om f pposi e ide thereof, ot a the forwa d an rearwa en hese; eet s rv n ff to u li b y fitted in the channels 16 of the r ceiver 11, and, as such, constrain backward and, return travel of. the breechtbolt assembly to the predetermined regiprocative, path established by such channels 16. I The housing 21 is longitudinally recessed. to slidably receive, through its rearward open end 21a, an inertia block; 213, which is somewhat. shorter than the effective length of the recessed interior of the housing 21, to per? utit o w r nd. rear rd mo em nt f the inertia block when the o h r is Ope e d .1 1 f he h u g s closed by remo ab e Such removable end wall 24 is advantageously slid-. yfit ed nto the housin t by ong e an groove members, collectively designated 25, Figs. 6 and 7, so as to be se re. a inst l n i u ina m e en y eas y em va le an ep ab One of the longitudinal sides of the housing 21 is open, but. an overhanging slideway member 21b serves to retain the inertia block 23 in place. Such block exte d h ou h sa openin to a po ition flush with he o te ll a e f t a longitudinal si e of the ho i g. as shown, see Fig. 8, so as to fill out the contour of the breech-bolt assembly and provide a convenient location for a return spring 26, Figs. 2 and 8, active upon the inertia block following firing and recoil.

Extractor Spent cartridges are extracted in customary fashion from the firing chamber of the gun by means of a conventional type of extractor 27, Figs. 6 and 7, resiliently mounted for transverse pivotal movement at the forward end of the housing 21, externally thereof.

Ejector A longitudinal groove 28, extending along the exposed side of the inertia block, and continuing along the housing 21, see 284, serves to accommodate a cartridge ejector pin 29, Fig. 8', projecting from the interior of receiverll opposite cartridge ejector part 17 of such receiver.

Automatic loading r h; eatttt aes 31. r ifted. fo owing respectiv firings and spent cartridge extractions and ejections, from. a position immediately to the rear of the magazine t be. 13, by meansof a cartridge carrier or lifter 32. Suchv lifter 32 is operated by the depressing action of he bre ehrb t assem ly n. a c ie spr g ev r 33 of he r e meeh s n 15,. s uch breech-bel as embly tra els.- le the t at been fir n he gun.- It w l b seen rem Figs. 2., 3., and 4,, that the. lever 33 is operaive n se ured to the. re rwar end of lifter 3.2 for thi purpose, by a resilient interconnection (not shown). to permit; depression of such lever by the breech-bolt assernbly even. though litter .32. is restrained. from rising. by stop mechanism described hereinafter.

Fresh cartridges 31 are urged rearwardly in magazine tube 13 by means of the customary spring (not shown), and are normally prevented from moving rearwardly by a stop member 34 depending centrally from the undersurface of breech-bolt housing 21 at the forward end thereof, see Figs. 2 and 3. As the breechebolt assembly moves backwardly upon firing of the gun, a fresh cartridge follows stop member 34 to a position upon the carrier or lifter 32.

The cartridge carrier or lifter 32 is restrained from commencing any upward movement until the breech-bolt assembly has completed its rearward travel. For this purpose, a spring loaded lever stop 35 is pivoted intermediate its length, as at 36, Figs. 2, 3, and 4, in an inner side wall of the receiver 11, so that its longer lever arm 35:! is normally urged inwardly of the receiver by spring 37-, to provide a stop against upward movement of the carrier 32. As a cartridge 31 is pushed from the magazine tube 13 onto the carrier 32, it slides against lever arm 35a, and gradually pushes such lever arm clear of the carrier, whereupon such carrier is free to move upwardly.

Because of the construction of lever 35, short leverarm 35bmoves outwardly, as a stop against the next cartridge in the magazine tube 13, when the long lever arm 35a is pushed back from its carrier stop position.

The breech-bolt assembly isrestrained from moving forwardly within the receiver 11 during an initial portion of the upward movement of the cartridge carrier 32. For this purpose, a spring-loaded latch 38, Fig. 5, projects upwardly from the trigger assembly 15, for engagement with a keeper 39 formed at the bottom of the breech-bolt housing 21. It should be noted that continued upward movement of the carrier 32 withdraws the latch 38from its keeper, and permits the breech-bolt assembly to move forwardly, and thus push the cartridge into the firing chamber of the barrel 12, thereby completing the loading operation.

Breech-bolt assembly in detail I The inertia. block 23 has its forward end recessed from top to bottom and from the front inwardly, as, a double-slot slideway for accommodating a locking bloclr 4.2. The, top and bottom walls of breech-bolt housing ,21 are ap rture in mutual r gistry; g.- 1, and 44, Figs. 6 and. 8, respectively, corresponding to. such ocking; blo k 42,. whereby the l king lock. is. free to move up ar ly an d ly relative to. the inertia block and the breech-bolt housing.

In this, connection, it should: be noted that, the recess 2t} at, the inner side of the top wall. of the. ret eiver 11 is formed to correspond with, and to snugly-th0llgh easily.receive, the locking block 42 when movement of the. breech-bolt assembly brings. the. latter into registry therewith.

The locking block 42 is coupled. to the. inertia block 23 by a cam type of slot and pin connection, see the arcuate slot 45 and pin 46., Figs. 6,. and 7, so that. n he normally maintained, rearward. position O he inertia block with respect to the breech-bolt housing 21, see. Big. 6, the locking block is raised into locking position, while in the inertia-induced forward position of such inertia block, see Fig. 7', the locking block is lowered or withdrawn, from its locking position.

Extending longitudinally of and completely through the assembly of breech-bolt housing, inertia block, and locking,- block is an elongate firing pin 47, having an attenuate portion 47a defined rearwardly by a pair- 0f cam surfaces 48, Figs. 6' and 7-.

The lockingbl'ock 42 is slotted upwardly from its bottom, as atv 49 Fig. 6, to, receive the forward tongue portion 23a of inertia block 23, and is re-entrantly slotted,

as at 50, Fig. 8, to snugly receive the attenuate portion 47a of firing pin 47.

For exerting a camming action on the firing pin when the locking block is moved downwardly from locked to unlocked position, those portions of the rearward face of such locking block 42which are laterally, marginal to re-entrant slotted portion 50-are formed as cam surfaces 51, Fig. 8, cooperative with respective cam surfaces 48. In this way, downward movement of the locking block into unlocked position positively retracts the firing pin, and holds it in retracted position until the locking block is once more moved upwardly into locking position. Accordingly, it is impossible for the firing pin to strike the primer of a cartridge 31 in the firing chamber of the gun, unless the breech-bolt assembly is locked in its forward or firing position within the receiver 11.

Breech-bolt return Following any given firing of the gun and travel of the breech-bolt assembly to the rear of the receiver by reason of the propulsive eifect of residual gases in the barrel, the breech-bolt assembly is returned to its for ward or firing position in the receiver by a spring 52 acting through an intermediate push rod 53.

The spring 52 is preferably encased within a tube 54, through whose open forward end the push rod 53 projects. The forward end of such push rod is preferably bifurcated, see Fig. 1, and bears against the rear end of breech-bolt housing 21, within respective recessed socket members 24a which project rearwardly from the outer face of removable end wall 24 of such housing.

Firing Firing of the gun is accomplished in the usual manner, by means of a trigger 55, operative in customary fashion to release a firing hammer 56, Fig. 3, which strikes the rear end of the firing pin 47. i

The firing hammer 56 is pivoted within the trigger plate 15, and is spring biased in any well known manner (not shown), so as to be depressed to its cocked position by the breech-bolt assembly 10 as such assembly moves toward the rear following any given firing of the gun.

Operation From the foregoing, it will be clear that, on any given firing of the gun by the customary pulling of trigger 55-assuming that the mechanism is in the locked firing position of Fig. 2, wherein the locking block 42 is in raised and locking position relative to keeper recess of the receiver 11, and firing pin 47 is free to move forwardly through slot 49 thereof-recoil action will throw the entire gun backwardly, but inertia block 23 will resist backward movement, and, through its linkage with the locking block, will withdraw such locking block from its locked position, see Fig. 3. Thus freed, the breech-bolt assembly 10 is propelled backwardly in the receiver by the force of residual gases in barrel 12.

In such backward movement of the breech-bolt assembly, extractor 27 removes the spent cartridge from the firing chamber, and ejector pin 29 pushes it from the receiver through ejector port 17. coincidentally, a fresh cartridge from magazine tube 13 follows the backward movement of stop 34 to a riding position upon carrier or lifter 32. v v

In its backward movement, the breech-bolt assembly depresses carrier spring lever 33, which urges cartridge lifter 32 to move upwardly against the restraining action of the stop lever arm 35a. Backward movement of the fresh cartridge pushes such stop lever arm out ofthe way at the appropriate time, thereby permitting the hitherto pent up urge of carrier spring lever 33 to act to raise lifter '32 and place the fresh cartridge, which it carries, in the path of forward travel of the breech-bolt assembly, see Fig. 4. I

Following the initial upward movement of cartridge carrier or'lifter 32, insured by the action of latch 38 on the breech-bolt assembly, release of the breech-bolt assembly enables the same to move forwardly in the receiver 11 under the urging of spring 52, and to push the fresh cartridgewhich by then is well within its path of action-into the firing chamber of the barrel 12.

It should be noted that spring 26 exerts an urge upon inertia block 23 to return it to its normal rearward position of Fig. 2, within the breech-bolt housing 21, after the effect of the recoil action is over. Such urge becomes effective when the locking block 42 is once more in registry with its keeper recess 20 in receiver 11. Accordingly, the breech-bolt assembly is automatically relocked in firing position upon its return to the forward part of the receiver, as in Fig. 2.

During the entire time that the breech-bolt assembly is displaced from its forward or firing position, the lowered position of locking block 42 means that the cam surfaces 51 thereof are in abutting relationship with the cam surfaces 48 of the firing pin, thereby positively preventing movement of such firing pin should the trigger be accidentally pulled. Only when such locking block is in raised and locking position, can the firing pin be made to strike the cartridge primer.

Lowering of the locking block immediately following the firing of the gun, in the manner explained hereinbefore, will, it should be noted, cause the cam surfaces 51 to exercise a camming action on the cam surfaces 48 of the firing pin, thereby positively retracting such firing pin to its original .position.

Manual operation As stated hereinbefore, provision is made for manually unlocking the breech-bolt assembly 10 in the receiver 11. For this purpose, a disk 60 is rotatably fitted into a suitable receiving recess provided in the inner face of the side wall of the breech-bolt housing 21, see especially Fig. 9, such disk having a pin 61 projecting rigidly from its back face into an elongate slideway 62, which is formed along the outer face of such side wall of the breech-bolt housing, and which intersects and opens into said recess.

The aforementioned slide 19, from which extends the thumb push 18, fits into and is adapted to slide within and along the slideway 62, whereby abutment of the free end portion of such slide 19 against the pin 61 effects a partial rotation of the disk 60.

A second pin 63, projecting rigidly from the opposite face of disk 60 at a point substantially diametrically opposite the pin 61, is received by a transverse slot 64 provided across the upper portion of inertia block 23, see Figs. 6 and 7, and pushes such inertia block forwardly in the breech-bolt housing 21--against the pressure of spring 26when the slide 19 is pushed backwardly by means of thumb push 18.

As a positive stop on the retractive stroke of the slide 19, a pin 65, Fig. 5, projects rigidly from the bottom of the slideway 62 into the path of movement of such slide.

Conclusion From the above description and explanation, it can be seen that the novel locking structure of the invention permits the advantageous assembly of barrel and magazine tube structure with the receiver, shown in Figs. 1 through 5, wherein the customary barrel extension is eliminated and the usual drop from the top of the receiver to the top of the barrel is considerably reduced. Futhermore, with the construction of the invention, unlocking of the breech-bolt assembly is effected without movement of the barrel relative to the receiver.

In addition to the foregoing, it can be seen that, in accordance with the invention, the firing pin is'positively locked against operation, and consequent firing of the gun, whenever the breech-bolt assembly is not locked in position at its forward, firing position in the receiver. Accordingly, a new and highly desirable safety feature is introduced into guns of the type concerned.

Whereas this invention is here illustrated and described with respect to a particular preferred form thereof, it should. be understood that various changes may be made therein, apart from the mere substitution of equivalents, by those skilled in the art and on the basis of theteachings hereof, without departing from the generic purview and scope of. the invention as defined by the following claims.

I claim:

1. In small firearm construction as described; wherein a breech-bolt assembly is slidably positioned within a re-. ceiver, for backward and forward longitudinal movement relative. thereto, and the barrel is fixed relative to the re-. ceiver, the combination of av locking latch block mounted in the breech-bolt assembly for up and down movement relative thereto and across its path of movement; means defining a keeper recess for said latch block, said recess being formed in the underside of the top wall, of the receiver in position for locking cooperation with the latch block when the breech-bolt assembly is in forward firing position in the receiver; a longitudinal slideway defined within said breech-bolt assembly; an inertia block slid-v ably mounted in said slideway, so as to substantially retain its. position, due to inertia, as the gun recoils upon firing, the forward end of said inertia block being formed with a vertical, double-slot slideway, and the latch block being bifurcated from its bottom upwardly, and slidably fitted within said double-slot slideway; resilient means normally urging said inertia element baekwardly within its said slideway; and cam linkage articulatively interconnecting said inertia block and said latch block, for withdrawing the latter from looking coaction. with said keeper recess during recoil of the gun, said cam linkage including a pair of registering cam slots of arcuate formation formed in respective opposite legs of said. latch block, and a pin fixed in and extending transversely through said inertia block and said cam slots.

2. The combination recited in claim 1, wherein the breech-bolt assembly includes an elongate firing pin extending longitudinally therethrough for sliding movement relative thereto; the latch block straddles said firing pin and. is. bifurcated to provide a slot and a re-entrant continuation thereof; and the said firing pin has anattenuate portion adapted for snugly fitting into said re-entrant continuation of the slot when said block is in lowered position, to lock said firing pin against firing movement.

3. The combination recited in claim 2, wherein the reentrant continuation of the slot and the attenuateportion of the firing pin are defined rearwardly by respective sets of coacting cam surfaces arranged to retract the firing pin. as the latch block is moved downwardly.

' 4, The combination recited in claim. 3, wherein man ually operable means are provided for unlocking the breechrboit assembly from the receiver, said means comprising a longitudinal slideway formed externally of. said breech-bolt assembly; a. manually operable slide mounted in said slideway; a pin projecting into the path of action of said slide within its said. slideway; a pin-receiving recess formed in the inertia block of said breechbolt assembly; a pin projecting into said recess; and fulcrumed lever 'm-eans interconnecting the first and second named pins.

5. In small firearm construction as. dQSQIibed', wherein a breech-bolt assembly is slidably positioned within. are; ceiver, for backward and forward longitudinal movement relative thereto, and the barrel is fixed relative to thereceiver, the combination of locking latch means in said breech-bolt assembly; corresponding keeper means defined inwardly of said receiver and positioned for looking cooperation with said latch means when the breechbolt assembly is in forward, firing position in said reeeiyer; a longitudinal slideway defined. Within said bree h-b 1 t assembly; an inertia element slidably mounted 1n,s a1d slideway, so as to substantially. retain its position due. to inertia, as the gun recoils upon firing; resilient means normally urging said inertia element backwardly within its saidslideway; cam linkage articulatively interconnect: ing said inertia element and said latch means, for withdrawing said latch means from locking coaetion with its. said keeper means during recoil of the gun; an elongate firing pin extending longitudinally through said breechbolt assembly, for sliding movement relative thereto, said. locking latch means being disposed for operation adjacent the line of. action of said firing pin; and coactive locking means provided by said locking latch means and saidfiring pin, respectively, for locking the firing pin against movement when the said locking latch means its retracted from looking position relative to the receiver.

6 The combination recited in claim. 5, wherein the coactive locking means include respective interacting earn surfaces directed to retract the firing pin uponretraction. of the latch means from its locking position relative to the receiver.

7. In small firearm construction as described, wherein a breechebolt assembly is slidably positioned within. a receiver, for backward and forward longitudinal movement relative thereto, and the barrel is fixed. relative tothe receiver, the combination of a breech-bolt housing; looking latch means inthe form of a block arranged in said breech-bolt housing for sliding movement transversely thereof; corresponding keeper means defined inwardly of said receiver and positioned for locking cooperation with said latch means when the breech-bolt assembly is inforward firing position in said receiver; a longitudinal slideway defined within said breech-bolt housing; an inertia element in the form, of a block slidably; mounted in said slideway, so as to substantially retain its position, due to inertia, as the gun recoils upon firing, said inertia block within its longitudinal extent being slidably interengaged with and carrying said lockinglateh block, and the latter projecting transversely of and beyond said inertia block into sliding interengagement with said breech-bolt housing; resilient means normally urging said inertia block backwardly within its said slideway; and cam linkage articulatively interconnecting saidinertia blocl; and said locking latch block, for extending and retracting the latter relative to the former, so as to withdraw said locking latch block from locking coaction with its said keeper means during recoil of the gun, said cam linkage comprising an arcuate cam slot and. a thereby received sliding pin arrangcment,

8.. The combination. recited in claim 7., wherein the locking latch block is arranged to slide upwardly and downwardly, and the keeper means is a recess formed in theunderside of the top wall of the receiver; wherein the forward endof the inertia block is formed with a vertical, double-slot slideway, the locking latch block is bifurcated from. its bottom. upwardly and is slidablyfitted within said double-slot slideway, and the. slot and'pincam link.- age arrangement comprises a pair of registering earn slots formed in. respective opposite legs of said locking. latch block, and. a pin fixed in and extending transversely through said inertia block and through said cam slots.

9.. The combination recited in claim 8, wherein the breechrbolthousing is provided with outwardly and laterally extending projections at opposite sides. thereof, and wherein the receiver is provided with longitudinally extending slideways disposed to receive said. projections, respectively,. and. to guide the. longitudinal sliding; movementof saidbreech-bolt housing.

10. In small firearm construction as described, wherein a breech-bolt assembly is slidably positioned within. a receiver,v for backward and forward longitudinal move.- ment relative thereto, the combination of. a locking latch block movable transversely in said breech-bolt assembly; corresponding keeper, means defined inwardly of said rem t e and rqs r qn d; f r ocki oopera io wi h; aid latch block when the breech-bolt assembly is in forward firing position in said receiver, said block beingfbifnrcated to provide a lo an re nt c t ua o her on. a firing pin operably mounted in and'sli'd'able longitudinally of said breech-bolt assembly, said firing pin having an attenuate portion adapted for snugly fitting into said reentrant continuation of the slot when said latch block is in lowered position, to lock said firing pin against firing movement; means urging said latch block in outwardly extended locking position relative to its said keeper means; means for withdrawing said latch block from said keeper means upon firing; and respective sets of coacting inclined surfaces formed by that portion of the latch block which defines said slot continuation and by the said attenuate portion of the firing pin, for retracting said firing pin when the latch block is retracted and for maintaining said firing pin in fixed retracted position when said latch block is out of locking engagement with its said keeper means.

References Cited inthe file of this patent UNITED STATES PATENTS Febiger Aug. 15, Freeman Nov. 12, Lovelace May 18, Chronis Nov. 5, Clarus Mar. 25, Chevallier et al Feb. 9, Stecke Aug. 10, Gal Mar. 12, Williams July 12, 'Tassan Oct. 31, Schnepel Apr. 29,

FOREIGN PATENTS Great Britain of 

